Electric motor-driven operator



Feb. i4, w50 E. A. REHWALB 2,497.9?94

ELECTRC MOTOR-DRIVEN OPERATOR Filed Nov. a, 1945 2 sheets-sheet l Feb. i4p i950 E. A. REHWALD 2,497,794

ELECTRIC MOTOR-DRIVEN OPERATOR 'Filed Nov. Sg, 1945 2 Sheets-Sheet 2 INVENTOR. Edmund A. Rehu/a/d BY v CMM, @@M'MJ, JJ/b.

ATTORNEYS Patented Feb. 14, 195.0

ELECTRIC MOTOR-DRIVEN OPERATOR Edmund A. Rehwald, Rockford, Ill., assignor to Barber-Colman Company, Rockford, Ill., a corporation of Illinois Application November 8, 1945, Serial No. 627,472

8 Claims.

-This invention relates to a electric motor driven operator for moving a device to be actuated back and forth through a predetermined distance in successive cycles of an electric motor which are started under manual control and terminated automatically. Such operators are usually started by a magnetic relay controlled from a remote point, and quick stopping of the actuated device is usually effected by an automatically applied friction brake which is released by a solenoid.

One object of this invention is to control the application and release of the friction brake in a novel manner.

A more detailed object is to release the brake directly from the motion of the relay armature whose switches control the starting of the motor.

The invention also resides in the simple construction of the brake control mechanism.

A further object is to provide for positively actuating the motor control switches to stop the motor in the event that the normally acting limit switches fail.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary side elevational view of an electric motor driven operator embodying the present invention.

Fig. 2 is a front elevational view looking in the direction of the arrows 22.

Figs. 3 and 4 are sectional views taken respectively along the lines 3--3 and 4--4 of Figs. 2 and 1.

Fig. 5 is a fragmentary elevational view of part of the brake actuator.

Fig. 6 is a circuit diagram.

The power operator shown for purposes of illustration comprises a reversible electric motor 6 operating through a coupling 1 and speed reduction gearing within a case 8 to drive a shaft 9'which is connected through a sprocket III and a chain I' to a device (not shown) to be moved back and forth through predetermined distances. The high speed shaft II carries a brake drum I2 whose external surface is encircled by brake shoes I3 pivoted at I4 and having parallel projections- I at their free ends on the other side of the drum. Springs I6 encircle a guide pin I9 and act in compression between the projections I5 and arms I1 of a bracket I 8 on the gear case 8. Separation of the projections I5 to release the brake is effected by a cam fast on a rockshaft 2| journaled at opposite ends in the bracket I8 and in a frame 22 on'the other side of the gear case. When the cam is in the neutral position shown, the shoes are collapsed around the drum by the springs I6 and the brake is applied to frictionally hold the shaft II against turning. Turning of the rockshaft and cam in either direction away from this neutral position results in sepa-ration of the projections I5 and the shoes I3 thereby releasing the brake.

Starting and stopping of the motor is controlled by the switches of magnetic contactors or relays 23 and '24 mounted side by side in the frame 22, the relays shown being of the type manufactured by The Square D Company. The relay 23 has switches 25 which are closed by upward sliding movement of a frame having an armature 2B pivoted thereon at 21, the armature being attracted to a magnet core by energization of a coil 28. Closure of the switches completes a circuit for the three phase windings 29 of the motor shown, the energization of which is maintained through a normally closed limit switch 39 of the microswitch type and a holding switch 3I which is closed when the relay 2B is energized. The relay coil 28 is energized in response to manual closure of a switch 32 located at a remote point of control and arranged in series with a switch 33' which is closed when the relay 24 is deenergized. The relay 24 is equipped with similar switches 25' (to energize the motor windings 29) and switch 3|' acting in conjunction with the limit switch 30 to hold the circuit for the winding '28', after this winding has been energized in response to manual closure of switch 32 arranged in series with switch 33 which is closed when the relay 23 is deenergized.

The pins 34 and 34 of the limit switches 30 and 3D' are actuated by cams 35 and 35 that travel back and forth along a screw 36 as the motor operates in opposite directions. This screw is journaled in the frame 22 and carries a sprocket 31 meshing with the chain I0 so as to move in unison with the device actuated by the motor operator.

When the switch 32 is closed with the parts positioned as shown, the coil 28 of the relay 23 is energized through the switch 33. The resulting movement of the armature 26 closes the switch 3| for holding the energization of the relay and .the switches 25 for starting the motor in a direction to advance the nuts 35 and 35 to the right as viewed in Fig. 2. The cycle is terminated when the nut 35 reaches the pin 34 and opens the limit switch 30 and the holding circuit thereby deenergizing the relay 23. Similar operation of the motor in the reverse direction takes place when the control switch 32 is again closed, this cycle being terminated by opening of the limit switch 3U' when the parts reach the position shown in Fig. 2.

In accordance with the present invention, provision is made for utilizing the motion of either one or the other of the relay armatures' 26 and,

26 to release the brake l2, l3- at the start of the cycles initiated by these armature motions.

To this end, the armatures are pivotally con-v nected at 38 and 38 with the endsof oppositelyprojecting arms 39 on a T-shaped bell crank pivoted on the frame 22 atlilfA to swing' aboutl an axis parallel to the brake' actuating rocksh-aft- -Y 2l. The bell crank has an arm 42 depending armatures to deenergize said motor.

2.. A power operator comprising, in combinay' tion, an electric motor, a shaft driven thereby, a

from the pivot and connectedV at its, lower end`- to one end of a link d3 whose other end is connected to a crank 44 fast on the end of the rock--y shaft 2i. When the relay 23 is energized, it will be apparent that therockshaft 2l andthe brake cam will be rocked counterclockwise as shown in Fig. 5, thereby releasing the brake against.Y

the action of the springs i6. In a similar way,

the cam will be rocked reverselyl to release the brake when the relay 24 is energized. In each instance, the-actuatedarmature will be moved..

upwardly and the brakes will be applied by the springs i6 when the-energized relay is deenergized by its limit switch inthe manner described above.

It will be apparent thatr the brake is actually released before the motor is energized instead of being actuated in thefusual. way by a separate solenoid whose energization is coincident with` the energization of the motor. Also, the brake is applied at the instant the limit until the magnetic contacter has dropped out after opening. of the limit switch. This results inv freer starting and quicker stopping. of the motor operator. At the same time, they structure and the circuit arrangements are greatly simplied. 'L -he brake itself is ofv ther` simple pivoted shoe type, and is equally effective in both' directions of motion of the actuating cam, whiley at the same time precluding` any uncontrollable self-energizing effect.

Provision is also made, as a safety measure. for positively'insuring deenergization of the mo-A tor if, for some reason, the limit switches fail to operateproperly.v For this purpose, the arnr 42 of the T-shaped` bell crank is` disposedadja-vcent the screw shaitS. and is provided with,

projections It and Q5" in the paths of the nuts 35 and t', the motor is not'stopped wheny the pin 34 of the limit switch is depressed by the cam- 35' as shown in Fig. 2,` the nut 35' will immediately engage the projection Yt5 and rock the bell crank topositively lower thearmature 2i?v and thereby break the motor circuit independently of; they; limit switch. Ina similar way, the-nut 35 will engage the projection 45 and rock the bell crank Y reversely to open the/switches of the contactor23 if the limit switch SG-Yfails' tofunction properly at the endof the reverse. cycle of the operator.'

I claim as my invention:

l. A power operator having, in combination, a reversible electric motor; a shaft driven thereby, a rcckshalit extending along the motor shaft? parallel thereto, a cam on said sh'aftar'ms pro-` jecting in opposite directions from a common pivot andv connected-tosaid rockshaft, magneticy relays having armatures Vconnected tothe respecswitch is opened, to deenergize the motor, instead of being delayed.

If, by` failure of the limit switch'.

mechanical frictiornbrake for retarding said v' shafthaving an actuating cam, said brake being applied by turning said cam in opposite directionsawayfrom normal brake-applied position, two magnetic relays having armatures mov- -able upon venergize-tion of the respective relays to initiate and maintainlzoperation of said motor inopposite' directions, lnreans connecting said armatures `to said cam to turn the latter in oppositedirections from saidV brake-applied positionv when the respective: 4relays are energized, and

" spring means actingto return said cam to said applied position when bothofgsaid relays are deenergized.

3.A power operato;1 havingQin combinationl areversible electricmotor, a shaft driven therebv,l two magneticzrelayswith armatures selectively energizable to initiateoperation of said` motor in opposite directionsand to maintain such operation; duringthe continued energization of the relay, a rockshaft connected to said arma- 'tures andturnedy in o ne.,` direction or the other outof a neutral position; according to which of said relays is energized, means normally urging said shaft toward said neutral, position, a brake for stoppingisaid driven shaf;t.when the motor:

isdeenergized, and means actuated by turning of saidrockshaft in. eitherI direction from said neutral position-tc; release said brake, said brake being app-lied automatically in the return of said roclrshaftI to said neutral position.

4. A power operatorhaving, in combination, a reversible electric meten magnetic relays having movable armatures,eirc.uits selectively energized by the, respectiverelays and operable to control,l the directionr and-'extentof operation of.

said motor according to which-'of the relays is energized, said circuitsincluding limit switches adapted when openedtoV deenergize the active relay, means driven.- by said motor and operable after predetermined rotationthereof to open theclosed limit switch and thereby deenergize the active relay and themotor, and means-mechanically connected to the armatures' of said relays and operable in the event .offai'lure of the active limit switch to mechanically-shift the armature of; the activerelay-` `to).deenergiz'ed positions.

5. A power operator havingin combination, a

reversible electric motor, a magneticr relay havingV amava-ble armature, a. circuit. energized. by the. relay and operable; 'tof control the starting and ,1 extent of` operation o f said motor; said circuit in.- cluding a limitfswitc'h: adapted when opened to'` deenergizevsaid relay; means. driven by'said motor f andoperable afterv predetermined rotation thereof to open vthe:closed-linut'switch. and thereby deenergize saidrelay andathemotor, and means mechanically :connected tothe` armature ofs'aid relay and-operable inthe-event of` failure ofV saidflirnitv switch to mechanicallyshift the relay V armature to deenergized 1 position.

6. A power operator having, in combination, a

operating with the surface to form a brake, spring means normally moving said element into gripping engagement with said surface, a rockshaft paralleling said motor shaft and carrying a cam normally disposed in a brake-applied position and operable .by turning of said rockshaft in either direction away from such position to actuate said element and release said brake, magnetic relays having armatures connected to said rockshaft to turn the latter in one direction or the other away from brake-applied position according to which of the relays is energized, and switches actuated by movement of the respective relay armatures to effect energization of said motor for rotation thereof in opposite directions.

7. A power operator having, in combination, an electric motor, a magnetic relay having an armature adapted to move between two positions to start and stop said motor when the relay is energized and deenergized respectively, an element connected to said armature and movable therewith along a predetermined path to a motor starting position and reversely to a motor stopping position, a member driven at a reduced speed by said motor along said path and in the motor stopping direction, said member being engageable with said element after a predetermined movement and operable to move the latter and said armature reversely to the motor stopping position, and a limit switch adapted to deenergize said relay and arranged to be engaged and actuated by said member before the latter encounters and moves said element.

8. A power operator having, in combination, an electric motor, a magnetic relay including an element movable between starting and stopping positions to start and stop said motor in response to energization and deenergization of said relay, a member driven by said motor after movement of said element to starting position and adapted after a predetermined rotation of the motor to engage said element and move the latter reversely froml said starting to said stopping position, a limit switch for effecting deenergization of said relay, and means actuated by said movement of said member and normally operable thereby to open said limit switch before the member encounters and actuates said element.

EDMUND A. REHWALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,744,228 Kaufman Jan. 21, 1930 1,923,034 Hendricksen Aug. 15, 1933 2,088,212 Milne July 27, 1937 2,175,037 Smith Oct. 3, 1939 2,214,807 Buckley Sept. 17, 1940 

